Fuel injection control system

Abstract

A fuel injection system including an arrangement for opening the injector valve after the engine has stopped so as to purge the injector of any accumulated fuel. The injection valve may be opened and closed through a number of repeated cycles which assist in the removal of carbon deposits or may be held open for a fixed time period. In addition, if the injector is of the air/fuel type, any compressed air in the chamber can be utilized to purge the fuel and also the opening of the injection valve will preclude the accumulation of air pressure in the system after the engine has been shut down.

I claim: 
     
       1. A fuel injector for an internal combustion engine, said fuel injector comprising a chamber into which fuel is delivered, a nozzle port for communicating said chamber with said engine, an injector valve for controlling the flow through said nozzle port, means for determining whether said engine is running or not, and means for opening said injection valve when said engine has stopped for purging fuel from said chamber. 
     
     
       2. A fuel injector as set forth in claim 1 wherein the means for opening the injection valve opens and closes the injection valve in a number of cycles after the engine has stopped. 
     
     
       3. A fuel injector as set forth in claim 1 wherein the means for opening the injection valve holds the injection valve open for a finite time period after the engine has stopped. 
     
     
       4. A fuel injector as set forth in claim 1 wherein the injector is a fuel/air injector and further including means for delivering compressed air to the chamber. 
     
     
       5. A fuel injector as set forth in claim 4 wherein the means for opening the injection valve opens and closes the injection valve in a number of cycles after the engine has stopped. 
     
     
       6. A fuel injector as set forth in claim 4 wherein the means for opening the injection valve holds the injection valve open for a finite time period after the engine has stopped. 
     
     
       7. A method of operating a fuel injector for an internal combustion engine wherein the fuel injector comprising a chamber into which fuel is delivered, a nozzle port for communicating the chamber with the engine, an injector valve for controlling the flow through the nozzle port, comprising the steps of determining whether the engine is running or not, and opening the injection valve when the engine has stopped for purging fuel from the chamber. 
     
     
       8. A method as set forth in claim 7 wherein the injection valve is opened and closed for a number of cycles after the engine has stopped. 
     
     
       9. A method as set forth in claim 7 wherein the injection valve is held open for a finite time period after the engine has stopped. 
     
     
       10. A method as set forth in claim 7 wherein the fuel injector is a fuel/air injector including means for delivering compressed air to the chamber and the opening of the injector valve purges compressed air trapped in the chamber along with fuel. 
     
     
       11. A method as set forth in claim 10 wherein the injection valve is opened and closed for a number of cycles after the engine has stopped. 
     
     
       12. A method as set forth in claim 10 wherein the injection valve is held open for a finite time period after the engine has stopped.